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Seizure‐onset zone localization by statistical parametric mapping in visually normal 18 F‐ FDG PET studies
Author(s) -
Mayoral Maria,
MartiFuster Berta,
Carreño Mar,
Carrasco Josep L.,
Bargalló Núria,
Donaire Antonio,
Rumià Jordi,
Perissinotti Andrés,
Lomeña Francisco,
Pintor Luis,
Boget Teresa,
Setoain Xavier
Publication year - 2016
Publication title -
epilepsia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.687
H-Index - 191
eISSN - 1528-1167
pISSN - 0013-9580
DOI - 10.1111/epi.13427
Subject(s) - statistical parametric mapping , concordance , confidence interval , nuclear medicine , medicine , positron emission tomography , epilepsy , epilepsy surgery , standardized uptake value , neuroimaging , radiology , magnetic resonance imaging , psychiatry
Summary Objective Neuroimaging is crucial in the presurgical evaluation of patients with medically refractory epilepsy. To improve the moderate sensitivity of [ 18 F]fluorodeoxyglucose–positron emission tomography ( 18 F‐FDG‐PET ), our aim was to evaluate the usefulness of statistical parametric mapping ( SPM ) to localize the seizure‐onset zone ( SOZ ) in PET studies deemed normal by visual assessment. Methods Fifty‐five patients with medically refractory epilepsy whose 18 F‐ FDG‐PET was visually evaluated as normal were retrospectively included. Twenty of these patients had undergone surgical intervention. PET images were analyzed by SPM 8 using a corrected p‐value of p < 0.05 and three uncorrected p‐values of p < 0.0001, p < 0.001, and p < 0.005, matched with minimum cluster sizes of k > 0, k > 20, k > 100, and k > 200, respectively. The SPM ‐identified potential seizure zone ( SZ ) was compared to the SOZ , which was determined by consensus during patient management meetings in the epilepsy unit, taking into account presurgical tests. Studies in which the SPM ‐identified potential SZ was concordant with the SOZ were considered “correctly localizing.” Results The SPM threshold combination with the least restrictive p‐value and greatest minimum cluster size achieved the highest rate of correctly localizing studies. When p < 0.005/k > 200 was used, 40% (22/55) of studies were correctly localizing, and the concordance obtained in the surgically intervened subgroup was substantial (к = 0.607, 95% confidence interval [ CI ] 0.258–0.957), which was comparable to the concordance obtained by magnetic resonance imaging ( MRI ) (к = 0.783, 95% CI 0.509–1.000). Significance SPM offers improved SOZ localization in 18 F‐ FDG‐PET studies that are negative on visual assessment. For this purpose, statistical parametric maps could be thresholded with liberal p‐values and restrictive cluster sizes.